Do I have biceps tendonitis?

Hey everyone. I trained my upper arms yesterday and since then, my biceps have been pretty sore. At first, I thought it was just muscle soreness because I was lifting heavier weights than usual, but I don't feel pain when I tense my muscles; I feel pain when I straighten my arm. As soon as I straighten my arm, I feel pain in my bicep near the inner side of my elbow. I don't feel like going to the doctor about something like this, so I asked here. What do you think?